This invention relates to a multipoint conductive sheet used as a connecting medium interposed between given two electronic parts.
Japanese Patent Unexamined Publication No. Hei 7-231019 discloses a multipoint conductive sheet having, as means for connecting a semiconductor wafer and a wiring board together, a plurality of conductive electrons arranged, in a multipoint fashion, on an insulative sheet such that the conductive electrons extend from a first main surface of the insulative sheet all the way to a second main surface through a thickness of the insulative sheet, each of the conductive electrons being provided at one end thereof with a first contact end which is arranged, in a multipoint fashion, on the first main surface and at the other end with a second contact end which is arranged, in a multipoint fashion, on the second main surface. In this prior art, each of the multipoint conductive sheet is formed of a flexible substrate 101 having a large number of bumps 104 arranged thereon in a multipoint fashion.
The multipoint conductive sheet is interposed between a semiconductor wafer and a wiring circuit board and pressurized in that condition, so that the first contact ends are contacted, under pressure, with corresponding electrode pads of the semiconductor wafer. The wiring board is then connected to a tester so as to be subjected to burn-in test. An anisotropic conductive rubber is interposed between the wiring board and the multipoint conductive sheet so that uniform electrical connection can be obtained by absorbing irregularity in height of the conductive electrons, warping of the wiring board, etc.
The multipoint conductive sheet formed on the flexible substrate has a large number of conductive electrons densely arranged in such a manner as to correspond to the electrode pads of the semiconductor wafer, and each conductive electron can displace in the direction of the thickness by flexure of the flexible substrate. As shown in FIG. 1, however, since the respective conductive electrons 2 are displaced while normally restricted by the flexible substrate 1, adjacent conductive electrons 2 are apt to co-displace as indicated by arrows and broken lines with the result that the conductive electrons 2 are incorrectly displaced relative to the corresponding electrode pads.